Sorry, I don't agree with using anything other than the actual speed limit data. You absolutely can not present an estimated speed limit as the 'speed limit'. That is wrong.
So you are going to tell the police that pulls you over for speeding: 'I am using Waze and it says the speed limit is 52 mph.' The police will respond: 'oh really, isn't that the free gps software that lets you report our speed traps, distract you when driving, and now makes up the speed limit? Well since you are so smart and the speed limit is actually 25 mph on that last curve I'm going to write you up for speeding, wreckless driving, and texting too. How about that!'
Wazer in San Diego, California USA and Tijuana, Mexico
iPhone 6 Plus, iOS 8.1.3, Waze 3.9